LSF-Insulated Cables – UK Overview

Low Smoke and Fume (LSF) cables are designed to emit reduced levels of smoke and acidic gases compared to standard PVC cables when exposed to fire. While they offer improved fire performance over traditional PVC cables, they still contain halogens and are not equivalent to Low Smoke Zero Halogen (LSZH) cables.

Key Characteristics of LSF Cables

• Modified PVC Composition: LSF cables are typically made from PVC compounds enhanced with additives to reduce smoke and fume emissions during combustion.

• Smoke and Gas Emissions: They emit less smoke and hydrogen chloride gas than standard PVC cables but still produce significant amounts of both.

• Lack of Standardisation: There is no universal standard defining LSF cables, leading to variations in performance between manufacturers.

Advantages of LSF Cables

• Improved Fire Performance: Compared to standard PVC cables, LSF cables produce less smoke and corrosive gases, enhancing visibility and reducing toxicity during fires.

• Cost-Effective: They are generally more affordable than LSZH cables, making them a budget-friendly option for certain applications.

• Flexibility: LSF cables maintain the flexibility of PVC cables, facilitating easier installation.

Limitations of LSF Cables

• Residual Toxicity: Despite improvements, LSF cables still emit significant levels of toxic gases and dense smoke, which can be hazardous in fire situations.

• Inconsistent Performance: Due to the lack of standardisation, the fire performance of LSF cables can vary, making it challenging to predict their behaviour in emergencies.

• Not Halogen-Free: LSF cables contain halogens, which can corrode electronic equipment and pose health risks during combustion.

Common Applications

• Commercial Buildings: Used in areas where improved fire performance is desired but LSZH cables are not mandated.

• Industrial Settings: Suitable for installations where some reduction in smoke and fume emissions is beneficial.

• Public Spaces: Employed in certain public areas, though caution is advised due to their residual emissions.

Relevant Standards

• BS EN 60332-1-2: Tests for flame propagation of single insulated wires or cables.

• BS EN 61034-2: Measures smoke density of cables burning under defined conditions.

• BS EN 60754-1: Determines the amount of halogen acid gas evolved during combustion.

Note: While LSF cables may meet some of these standards, they are not required to meet the stringent criteria set for LSZH cables.

Maintenance and Safety Considerations

• Regular Inspection: Monitor for signs of degradation, especially in environments with high temperatures or chemical exposure.

• Appropriate Usage: Avoid using LSF cables in areas where halogen-free materials are specified or where maximum fire safety is critical.

• Manufacturer Verification: Due to performance variability, verify the specifications and test results provided by the manufacturer.

Summary Table

While LSF cables offer certain advantages over standard PVC cables in terms of reduced smoke and fume emissions, they are not a substitute for LSZH cables in environments where halogen-free materials are required. Careful consideration of the specific application and adherence to relevant standards are essential when selecting LSF cables.